A non-radioactive substitute for uranyl acetate with comparable results. Avoids the tedious authorization, shipping and disposal issues involving uranyl acetate without sacrificing performance. Two lanthanide salts, samarium and gadolinium triacetate, effectively used for positive staining of plastic-embedded animal and plant tissues. Also for negative staining of macromolecules. Not recommended as a fixative.This item is not a DG. Can be shipped in Limited qty.